CSS: more 1471 fixes

[toad]

A few minor fixes to the CSS changes. Removes some keywords that shouldn't be allowed, adds some that should. Can wait.

[Thynix]

What does it add? I only see removing "space-between", "space-around", and "space-evenly" from "align-items". What does the "justify-items" change fix?

[Thynix]

It removes left, center, and right - the strings are references to other array indexes.

[Thynix]

Er, I'm wrong. I still don't understand what exactly it changes.

[Thynix]

I think I got it now?

For it used to accept "left legacy", "center legacy", "right legacy", "legacy left", "legacy center", or "legacy right" before or after "center", "start", "end", "self-start", "self-end", "flex-start", "flex-end", "left", or "right". Instead of the former set it now only accepts "true" or "safe".

I still don't understand why though.

[Thynix]

Why change justify-items? The spec indicates the previous values were accepted, does it not?

[toad]

align-items doesn't accept the 3 keywords I deleted.

[Thynix]

Okay, but what about justify-items?

[toad]

justify-items accepts any one of the auxiliary verifiers 125, 129 and 130.

125 is auto, stretch or baseline-position.
129 is the last bit: legacy && [left|right|center]: legacy left, right legacy, center etc.

• This is made of 128 (legacy) and 4 (left|right|center)
  That leaves 130 which should be "item-position && overflow-position?" e.g. "start true" etc.

The new code has 130 = combinations of 122 and 126. 122 is overflow-position, 126 is item-position.
The old code had 130 = combinations of 129 and 126. This is incorrect - we don't want the legacy keyword here, and there are more item-positions than left, right, center.

[Thynix]

Alright, so. We finally got me to understand this:

<justify-items> used to accept <item-position> along with legacy && [ left | right | center ], which is incorrect. It now accepts <item-position> along with <overflow-position>, to match http://www.w3.org/TR/css3-align/#justify-items-property